Most of medicaments having an amidino group are circulatory agents, and others thereof are anti-histamic agents and few thereof are central nervous system-acting agents (Progress in Medicinal Chemistry, Vol. 30, pages 203 to 326, 1993, published by ELSEVIER CO., LTD.). As an anti-inflammatory agent, there are only naphazoline (for rhinitis) and the like (Progress in Medicinal Chemistry, Vol. 30, page 257, 1993, published by ELSEVIER CO., LTD.). However, all of the chemical structures of these agents are those having an amidino group at the end of the molecule and not those having an amidino structure intermediate between a thiophene ring and a phenyl ring as proposed by us in this invention. With respect to medicaments having a thiophene ring, those having anti-inflammatory action are disclosed, for example, in JP,B,3-14312 and International Publication WO 91/19708 (Tokuhyo-Hei 6-501919). However, none of them have an amidino group. Thus, the compounds proposed by us have a structure containing a phenylamidino group, which structure is entirely different from those of conventionally disclosed anti-inflammatory agents.
With respect to pharmacological action of anti-inflammatory agents, it is recognized that non-steroid anti-inflammatory agents clinically widely used, such as aspirin and indomethacin, exert anti-inflammatory action through inhibition of the activity of cyclooxygenase (synthetase of prostaglandin G/H) which is a rate-determining enzyme of prostaglandin production. However, cyclooxygenase exists not only in inflamed regions but also in various tissues and it is recognized that the inhibition of cyclooxygenase activity relates to side effects of non-steroid anti-inflammatory agents on digestive organs or kidney. Lesion of digestive organs among the side effects is a significant factor in limited clinical applications of non-steroid anti-inflammatory agents.
It is an object of the present invention to provide a novel and useful phenylamidinothiophene derivative and a salt thereof showing an anti-inflammatory action without causing lesion of digestive organs.
Another object of the present invention is to provide a medicament containing the phenylamidinothiophene derivative or a pharmacologically acceptable salt thereof as an effective ingredient for the prevention and/or treatment of inflammatory diseases and other diseases mentioned above without causing lesion of digestive organs.